Technical Field
Embodiments of this invention relate to an image forming apparatus, such as a copier, a facsimile machine, a printer, etc., that includes an electric charge removing device that diselectrifies an electrostatic latent image bearer after a transfer process is applied thereto by a transfer device.
Related Art
In a common image forming apparatus that employs an electrophotographic system, an image is formed by executing the below-described processes.
That is, an electrostatic latent image bearer such as a rotary photoconductor, etc., is initially electrified uniformly by an electric charging unit. An optical writing process (e.g. an exposure process) is then applied to the electrostatic latent image bearer by an optical writing device such as optical scanning device, etc., to form an electrostatic latent image on the electrostatic latent image bearer. The electrostatic latent image is then rendered visible by a developing device as a toner image. The toner image obtained in this way is subsequently transferred onto either a recording sheet or an intermediate transfer member or the like by a transfer device, such as a transfer roller, etc., from the electrostatic latent image bearer. Some toner generally remains on the surface of the electrostatic latent image bearer after completion of the transfer process, but is removed therefrom by a cleaning unit after that. In addition, after the transfer process is completed, some electric charge also generally remains on the electrostatic latent image bearer. However, since such residual electric charge sometimes generates an afterimage, the residual electric charge is accordingly removed by an electric charge removing device such as an electric charge removing lamp, etc.
In an attempt to prevent afterimage formation, comparative image forming apparatuses employ a second electric charging unit such as a corotron charger (i.e., an electric charging device using corona discharge) separate from a first electric charging unit that uniformly electrifies a surface of an electrostatic latent image bearer to apply a prescribed bias voltage to the surface of an electrostatic latent image bearer while having a polarity opposite to that of a bias voltage applied thereto by a transfer device before the electric charge removing device removes the residual electric charge thereon. That is, the comparative image forming apparatus attempts to prevent occurrence of the afterimage.